Authentication with x.509 in sharded cluster

I am triying to verify that authentication with x.509 is enabled in sharded cluster, but the chain conection that the admin uses is something like that:

mongo --host hostname --port 27000 --tls --tlsCAFile pathcafile -u user -p

I can see that the – --tlsCertificateKeyFile option is missing so it doesn’t required de server certificate and options --host and --tlsCAFile are to connect to a mongos instance that requires encrypted communication, I mean, it only encrypts communication.

Also -u and -p options wouldn’t need if authentication with x.509 was enabled.
So I can conclude that authentication with x.509 is not enabled, this is correct? could you help me?

thank you